In pressurized water reactor (PWR), including Russian design VVER (Vodaa Vodiannee Energititscherski Reactor, in English Water Water Energy Reactor), or boiling water reactor (BWR) or pressurized heavy water reactor (PHWR), each nuclear fuel rod comprises a pile of sintered fuel pellets surrounded by a cladding. A fuel pellet is obtained by sintering of a green fuel pellet mainly made from uranium oxide with any content of the isotope 235 and/or from plutonium oxide, with possible addition of burnable poison, such as for instance Gd2O3.
A fuel pellet of the above-mentioned type is known from WO-02/45096. A dish-shaped recess is provided at the center of the end face around the central axis, the chamfer and the recess being joined by a flat surface.